Add post autosave for title generation and content resizing.

[iamdharmesh]

Description of the Change

PR adds autosave functionality for post title generation and content resizing when the post is not dirty (meaning it doesn't contain any other changes). This addition aims to keep a record of every small change made by classifAI, and the editor can restore previous post content by utilizing WordPress core's revision functionality.

Note: Autosave has not been added to excerpt generation yet, as it directly replaces the post excerpt before manual human review.

Closes #590

How to test the Change

1. Create/Edit any post.
2. Click "Generate titles" without making any changes to the post.
3. Verify that the post title value is updated and the post is also saved.
4. Make changes in post content.
5. Click "Generate titles".
6. Verify that it only updates the title value without saving the post.
7. Verify this with the classic editor.
8. Test the same with Resizing content.

Changelog Entry

Added - Post autosave for title generation and content resizing.

Credits

Props @jeffpaul @iamdharmesh

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests pass.

[dkotter]

Does this trigger an autosave or a normal save? Or maybe in Gutenberg it's the same thing? I'm seeing the saveEntityRecord function has an isAutosave option but don't see the same in this function, so just want to ensure we're using the right thing here

[iamdharmesh]

Does this trigger an autosave or a normal save?

@dkotter this is a normal save. As Gutenberg provides information on whether the post is dirty or not, we can make sure that the post doesn't contain any other changes than our changes, we are good to trigger the normal save here. Please let me know if you think we should trigger autosave here instead of the normal save.

Or maybe in Gutenberg it's the same thing?

Normal save is different from autosave in Gutenberg as well, like the classic editor.